There is a critical need to develop better measures to assess adjustment to mechanical circulatory support (MCS) and health-related quality of life (HRQOL) because the impact of this therapy on patients' lives is profound. MCS devices are implanted surgically in patients with advanced heart failure and help the heart pump blood throughout the body. After discharge from the hospital, patients manage and troubleshoot their MCS devices while returning, as best they can, to usual activities of daily living (e.g., home and family responsibilities, work, and recreation). Benefits of MCS include longer survival (as compared to medical management of advanced heart failure), reduced heart failure symptoms, and improved physical function. Device-related complications (including bleeding, infection, device malfunction, and stroke) are risks of MCS implantation. As MCS technology evolves, survival is improving and the risk of adverse events is decreasing. However, future recommendations on the advisability of this expensive technology will depend not only on survivability and the risk of adverse events, but also on other outcomes, such as adjustment to MCS and HRQOL, which are less well defined. Importantly, currently available HRQOL instruments, which are generic or designed for heart failure or other illnesses, do not address many of the issues of concern and unique burdens of MCS on patients' daily lives. Currently, 50,000 to 100,ooo patients are diagnosed with advanced heart failure annually. Given the limited availability of heart transplantation, advanced heart failure patients may be offered MCS as a permanent implant (i.e., destination therapy). We propose to develop an MCS-specific measurement system, which we will refer to as Mechanical Circulatory Support: Adjustment and Quality of Life (MCS A-QOL). Our study design will focus on development and psychometric testing of our MCS A-QOL measurement system and evaluation of our conceptual model, followed by an exploration of usability of our measures (via a mobile app) by patients and providers. With development of a measurement system, our research will advance the field of MCS in patients with advanced heart failure. Use of our valid and responsive MCS A-QOL measures will contribute significantly to more clearly defining the benefits and risks of this evolving technology as compared with medical therapy or other strategies. Thus, survival will become more meaningful, as MCS A-QOL is incorporated into our understanding of risks and benefits.